If you want to give this a roll and you don't have lapidary graded alumina... Shake some Shapton fine stone lapping compound on a soft Ark and give it a whirl. Oil works great. Water seems to cut faster, but it produces a very even, dull mat finish with this compound. It behaves like it has some sort of cleaner mixed in, which slightly etches the steel. Marketing ad copy says ~4000 grit (JIS.). I had some from a project years ago and it works quick but leaves a finish like you'd expect from that grit level. Don't like it? Scrub it off with soap and hot water, and off you go.
I suppose if you were really curious, you could scrape a blob of mud off a fine grit water stone and smear it on a soft Ark and give it a whirl. I bet you would be surprised by how nice it works. I certainly was.
Interestingly, assuming soft Arks that don't throw sand, they behave more like a substrate than the stone they once were. Each alumina grit produces an incrementally finer finish that tracks the abrasive more than the soft Ark. So, for example, the 1-3 micron polish leaves a much finer finish than I ever got with the soft Ark alone.
Unfortunately, my phone doesn't take the sort of pictures which are useful for showing the differences in finish, but they are significant. I personally doubted that 1-3 micron alumina would do anything useful on a soft Ark, but it really does. I don't own any water stones, but the finish it leaves is finer than a DMT ultra fine (3-micron).
Going through the grits is quick as well. None of them took more than 2-dozen strokes on a 20-degree full flat bevel. Teasing off the wire edge is fast and painless on the fine polish treated ark. That surprised me, as with untreated stones, I could get there, but it was ssslllooooowwww.
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Originally Posted by John C Cox
